1. Field of the Invention
The invention relates to an antenna, and in particular to a wideband antenna.
2. Description of the Related Art
GSM 900 and DCS 1800 signals are widely utilized in cell phone communication to transmit audio and visual data. FIG. 1a shows a conventional flat antenna 1 to transmit GSM 900 and DCS 1800 signals, disposed in a cell phone, comprising a radiator 2 and a signal line 3. The signal line 3 is electrically connected to the radiator 2. With reference to FIG. 1b, when the flat antenna 1 transmits GSM 900 signal, a bandwidth thereof (bandwidth is defined as signals having voltage standing wave ratios lower than 4) is about 70 to 80 MHz, and when the flat antenna 1 transmits DCS 1800 signal, a bandwidth thereof is about 140 to 150 MHz.
Wireless communication, particularly long distance wireless transmission and wideband transmission, has become a necessary feature for portable electronic devices (for example, notebooks). Additionally, since communication standards for various areas are different, portable electronic devices are required to transmitting wireless signals under a variety of communication standards, such as AMPS(824˜894 MHz) {grave over ( )} PCS(1850˜1990 MHz) {grave over ( )} GSM(880˜960 MHz) {grave over ( )} DCS(1710˜1880 MHz) {grave over ( )} PDC(810˜915 MHz) {grave over ( )} PHS(1895˜1918 MHz) {grave over ( )} GPS(1575 MHz) and UMTS(1920˜2170 MHz). The conventional flat antenna 1, however, has a narrow bandwidth, poor compatibility, and decreased transmission speed, such that it cannot satisfy wideband transmission requirements.
U.S. Pat. No. 6,903,690 discloses a conventional antenna. The conventional antenna, however, has a narrow bandwidth, such that it cannot satisfy wideband transmission requirements.